World's biggest bond trader got start gambling. Duke grad arranged a Kentucky Derby pool in college; spent a summer as a slots worker at Harrah's in Lake Tahoe. Then Vegas: turned $200 into $10,000 in 4 months playing blackjack. M.B.A. from UCLA, became securities analyst at Pacific Life. Discovered how to make money with bonds: trade, don't buy and hold. Handed $10 million portfolio to manage 1973; earned $20 million bonuses 1980s. Bond division spun off to create Pimco. Public 1994. Sold to German insurance giant Allianz AG for $4.7 billion in 2000; personally made more than $400 million. Avid collector owns every stamp produced in the U.S. between 1847 and 1869, including rare "Z Grill" depicting Benjamin Franklin; only 2 known to exist.

Distribution of Billionaires by Residence

Diameter of disc reflects size of fortune. The red disc indicates William Gross